In large scale multiple needle quilting machines, several layers of fabric web are brought together at a quilting station where they are sewn together by the stitching of patterns thereon. The patterns are formed by moving the composite multiple layered fabric web relative to a bank of stitching elements that include an array of needles above the fabric and a corresponding array of loopers or other cooperating stitching elements below the fabric supported on a needle plate. The relative motion of the fabric and the stitching elements is often carried out under the control of a cam driven mechanical or electronically programmable controller. The programs of the controllers are varied in order to produce a variety of patterns to satisfy the requirements of the customers of the quilted fabrics. These customers are often the manufacturers of mattresses and other upholstered items, whose requirements are varied. Such customers of a quilt manufacturer may each order a number of different patterns in small or moderate quantities, requiring the quilt manufacturer to frequently change the pattern program and possibly also the fabric material.
When quilts are stitched on multi-needle web fed quilting machines, a series of a panel-length sections of quilted patterns emerge from a downstream end of the quilting station of the quilting machine as part of a single continuous web. The series might include multiple copies of the same pattern sewn on the same material, a series of different patterns sewn on the same material, or a series of the same or different patterns sewn on different types of material spliced together to form the continuous web. The series of panels quilted on the web are then severed into finished quilted panel lengths, often on a panel cutter situated either downstream of the quilting machine and through which the quilted web is fed or off line into which a quilted web must be fed after being quilted and then folded or rolled. In many quilt making facilities, quilting machines operate independently of the panel cutters and the coordination between the quilting and panel cutting operations is manually controlled.
To automate production of various types of panels or batches of panels, quilting machines have been provided such as that disclosed in U.S. Pat. No. 5,154,130 entitled "Multi-Needle Double Lock Chain Stitch Tack, Jump and Thread Trimming Quilting Method and Apparatus", which is assigned to the assignee of the present application and is hereby expressly incorporated by reference herein. Such quilting machines include controllers programmed to cause movement of fabric relative to the stitching elements to produce the various patterns and to change from pattern to pattern in accordance with different jobs of a production schedule. Such machines may also signal the need to change and splice materials where called for by an order description.
Each of the panel length sections of quilted web that emerge from the quilting station must ultimately be cut from the web to form individual quilted panels. This has often been achieved by placing in line with and downstream of the quilting station a panel cutter that includes a transverse knife or blade that is intermittently actuated to cut transversely across the quilted fabric to separate the individual panels from the web. The quilting of patterns onto a web and the cutting of discrete panels from the web requires coordination of the panel cutter knife and the quilting station as well as the location of the splices in the fabric. This coordination has been carried out either with manual monitoring by an operator and manual decision making or by an automated quilting and panel cutting machine such as that disclosed in U.S. Pat. No. 5,544,599 entitled "Program Controlled Quilter and Panel Cutter System with Automatic Shrinkage Compensation", assigned to the assignee of the present application, hereby expressly incorporated by reference herein.
The coordination of a panel cutting operation with a stitching operation and the splicing of material in a web that is being formed into a series of quilted patterns is complicated by the phenomenon referred to in the quilting industry as "shrinkage". Shrinkage of the fabric is a result of the stitching together of multiple layers of fabric that include the top and bottom layers with a filler layer in between. As the layers are stitched together, the material tends to gather, causing the fabric to shorten dimensionally in the longitudinal direction along the web. The longitudinal shrinkage is the primary complicating factor in coordinating the operations on the web. The amount of shrinkage varies among different patterns, due to the different amounts and configurations of the stitching called for by the patterns. Fabric is under tension in the quilting machine has its longitudinal dimensions affected slightly but materially by shrinkage, but when tension is released, shrinkage is manifested in a greater shortening of the fabric. Shortening may vary without a change in the patterns or the material due to ambient factors such as humidity in the plant.
The dimensions of the cut unstressed panels are the dimensions to which the quilting, splicing and feeding of the web must be coordinated, since these are the specified dimensions of the finished product. In order to produce a panel of a given length, a section of the web of a somewhat greater length must be quilted, and the position and dimensions of the quilted patterns on the web must be adjusted to accommodate for the shrinkage that will occur. In addition, due to the shrinkage, the rate of feed of web through the quilting station and through the panel cutter will differ. This shrinkage compensation is accounted for manually by an operator of mechanical and stand-alone quilting machines by timing the ON and OFF functions of the quilter or by adjusting the longitudinal scale of the pattern. The system described in U.S. Pat. No. 5,544,599 coordinates the quilting operations and panel cutting operations of an integral quilter and panel cutter system while adjusting the stitching and web feed to the quilting station so as to compensate for such shrinkage so as to deliver specified panel lengths to the panel cutter.
Cumulative effects of shrinkage are taken into account either manually or automatically by the system described above to minimize waste when different materials must be spliced together and to synchronize the cutting of panels precisely between the patterns.
A variety of quilting machines are being used in quilt manufacturing, including web fed quilters of types used to quilt mattress covers from web fed material. Many of these machines are either manually controlled or are necessarily provided without integral panel cutters. As a result, the addition of panel cutting operations to the quilting line brings with it the need to manually coordinate the quilting and panel cutting operations in a way that deals with the problems discussed above. As a result, the quilt making process is undesirably operator intensive and system throughput is limited by the frequent operator intervention.
Accordingly, there is a need to accommodate the variety of quilting machines being used in quilt manufacturing industry, particularly web fed quilters used for mattress cover manufacturing as well as other types of quilters used for other quilted products where trimming or panel cutting or other series operations must be performed on the material. Such need includes the need to synchronize machines that have been manually controlled or do not include integral panel cutter controlled operation. There is a particular need to coordinate the quilting and panel cutting operations when panel cutters are supplied in line with stand-alone quilters and other quilters that do not have shrinkage compensation or panel cutter coordination capability. There is a further need to generally make the quilt making process less operator intensive and to make system throughput less limited by the operator intervention.